如何正常关闭芹菜的花朵？

Question

当我发送SIGTERM时，花朵有时会死于此异常，并且它的数据库不包含最新任务。

File "/home/devil/envs/celery/lib/python3.6/
site-packages/flower/app.py", line 68, in stop
    self.events.stop()
File "/home/devil/envs/celery/lib/python3.6/
site-packages/flower/events.py", line 98, in stop
    state['events'] = self.state
File "/usr/lib/python3.6/shelve.py", 
line 124, in __setitem__
    p.dump(value)
RuntimeError: OrderedDict mutated during iteration

是否可以正常关闭flower？